Bolt for peeling coating film

Abstract

A bolt for peeling a coating film of the present invention includes notch parts for peeling a coating film, the notch parts being formed over a plurality of pitches at top parts of screw threads in a male screw part formed in a shaft part. The bolt is characterized in that the respective notch parts formed over the plurality of pitches are arranged to be greatly inclined at an angle of 40° to 50° to an axial line of the shaft part. Since the respective notch parts can be rolled sequentially, it is possible to form the notch parts to be deeper and sharper than conventional ones and to enhance the coating film peeling performance. Also, the coating film peeled can be discharged efficiently as compared with conventional cases.

The invention claimed is: 
     
       1. A bolt for peeling a coating film, the bolt comprising a shaft part, which has an axial center line, and notch parts for peeling the coating film, the notch parts being formed over a plurality of pitches at top parts of screw threads in a male screw part formed in the shaft part, with each notch part comprising a gentle slope having a shape that has a narrow extending width and a steep slope having a shape that has a broad extending width such that the gentle slope and the steep slope are connected at their respective widest widths so as to have a root line lying therebetween,
 wherein the root line in the respective notch parts formed over the plurality of pitches are arranged to be inclined at an angle of 40° to 50° from the axial center line of the shaft part. 
 
     
     
       2. The bolt for peeling a coating film according to  claim 1 , wherein the notch parts have the gentle slope on a leading side in a driving direction and the steep slope on a trailing side in the driving direction. 
     
     
       3. The bolt for peeling a coating film according to  claim 1 , wherein the male screw part has a normal screw part formed on the base end side of the shaft part and a non-normal screw part framed on the tip end side relative to the normal screw part; the non-normal screw part is formed to have a root diameter deeper than that of the normal screw part and a flank angle steeper than that of the normal screw part; and the notch parts are formed in the non-normal screw part. 
     
     
       4. The bolt for peeling a coating film according to  claim 3 , wherein the notch parts are formed to have a depth shallower than the valley of the non-normal screw part. 
     
     
       5. The bolt for peeling a coating film according to  claim 3 , wherein the non-normal screw part is formed to have a following flank angle steeper than a leading flank angle. 
     
     
       6. The bolt for peeling a coating film according to  claim 3 , wherein the leading flank slope of the non-normal screw part is formed in an irregular shape such that it is bent at the top part of the screw thread.